Pages

Tuesday, October 29, 2013

The "worm" body plan is a successful one. A head. Bilateral symmetry. Long body. That makes a lot of sense. The head takes the lead and you've got a long, slender body which facilitates success for moving through crevices and such. This has been thought by some to be the body plan for the very first metazoan predators (although not all with the body plan are predators).

Image by Divaholic

There's versatility in feeding and life modes... and the body plan is observed in multiple PHYLA (major grouping) of animals (e.g., annelids, flatworms, etc) and even in other groups which don't primarily have a "worm" like body plan (e.g., aplacophorans in molluscs, sea cucumbers in echinoderms, snakes in vertebrates).

Curiously, there's something ABOUT animals with this body shape that seems to freak people out.

Is it the body shape? Something left over from our "metazoan" brain from a LONG time ago?

People hate snakes. They always use 'mealworms" (actually beetle larvae) on monster and horror films and TV (totally harmless btw). Heck, earthworms are HARMLESS (at least to people) and you can still totally squick most people out by dangling one in front of them!

Image by Mely-o

So what if we looked at worms that are actually PREDATORS? That feed on prey in really graphic ways??

Its Halloween week! Here's FIVE disturbing predatory worms!

Imagining ANY of these as human sized or above would be cause for alarm!

So, I know 46 year old men who STILL get freaked out by Bobbit Worms. Even after all the reassurances and graphic photo evidence PLUS the knowledge that they will never go SCUBA diving in the tropical Pacific!!

Wanna see WORSE than the Bobbit worm?? Let's GO!

2. Ribbon Worms-Long distance Death!

Ribbon worms, also known as Nemerteans, are an obscure phylum of worms that are similar in appearance to flatworms (below) BUT one of the big differences is that Ribbon Worms possess a CRAZY long proboscis!

Basically the proboscis is an extended feeding structure used for a FAST grab which in some cases, extends easily 100% of the worms body LENGTH!

Ribbon worms really need to be seen to be appreciated. So here's some video!

Feeding in this worm, is to put it mildly, HORRIFIC. The marine Euplanagracilis is a flatworm that consumes its prey by LITERALLY sucking out its guts, while the prey is still ALIVE!

I'll let the video's author comment:

In this video, Euplana attacks a shrimp-like amphipod by wrapping around its back and completely immobilizing it. Sticking its tube-like pharynx through a segment of the amphipod, the flatworm then consumes and digests its internals--a process that takes about half an hour. Once finished, it abandons the empty carcass and goes into a resting period until its next meal. On the outside, an amphipod that's been eaten doesn't look that different from a normal amphipod...except for the fact that it's, well, dead.

Flatworms that live on the land are seen uncommonly but they're there. And they are mean, vicious predators. I wouldn't have known or even thought to think that, but here we go...

Here is Bipalium, a widely known genus of terrestrial flatworm. Originally from Asia, they've since been introduced all over the world. In their natural habitat, they have these really gorgeous, bright colors....

image by pbertner

Bipalium feeds on earthworms, so much so that they will inspire an immediate escape response whenever they are put in contact with one (see the video below).

Ever see an earthworm literally JUMP in sheer terror? Watch this...

Here's the feeding dance blow by blow... The worm's head approaches the worm and applies digestive enzymes. It physically begins digesting its prey WHILE THE PREY IS ALIVE...

Image by Amuderick

It digests its meal as a dissolved earthworm milkshake...

Image by Cornell Fungi

BUT its not just the one to one predation which is a concern. TOO many of these predatory land flatworms can actually affect the large-scale ECOLOGY of a region if they devour all the earthworms!

There's marine leeches, terrestrial leeches and of course, freshwater leeches such as the Giant Amazon Leech pictured above! It reaches a length of frakking 18 inches long!! and feed on mammals that happen to stop by to drink...

Wednesday, October 23, 2013

PARIS! I've just arrived and hard at work with my colleagues at the Museum national d'Histoire naturelle! But this week has been crazy. Wi-fi down, taking care of last minute projects and so forth on top of travel and jet lag.

So this week the blog is about a curious set of street art I've seen. OCTOPUSES all around Paris!

These are often painted or posted surreptitiously around Paris in strange corners and rarely travelled nooks around the city. Based on the arm length and overall appearance they appear to most closely resemble the "dumbo" octopus -something like Grimpateuthis or Opisthoteuthis but I'm pretty sure the artist has mainly taken the image from his own imagination...

Why Should We care?
With all the media picking up the story and carrying it around to multiple outlets, at some point someone will get beyond the "weird news" twist that has been put on the articles and ask "So What?" Here are 5 reasons I think understanding why this die-off MUST be studied.1. An Endemic Starfish Fauna.

Basically, one of the important facts was that all of the asteriid starfishes in this area, including Pycnopodia (the sunflower starfish), Pisaster (the ochre star), Evasterias, Leptasterias, etc. on the Pacific coast of North America are ENDEMIC TO THE COAST.

That means, you could see a starfish which resembles Pycnopodia in Australia or Mexico and it will have LESS relationship to Pycnopodia than Pycnopodia has to Pisaster!

Bottom line: You won't find these starfish species anywhere else in the world. These animals are an important part of the marine ecology of the Pacific coast of North America.2. Aesthetic & Cultural History

Image by sjonnie van der kist

“What do they find to study?” Hazel continued. “They’re just starfish. There’s millions of ’em around. I could get you a million of ’em.”
“They’re complicated and interesting animals,” Doc said a little defensively.

If this isn't a communicable disease per se but is instead more of a series of symptoms related to poor or changing environmental factors, which activates/corrupts/modifies that fauna, THAT could be a concern which leads us to our next point...

5. Widespread Ecological Impact. Here's the million dollar issue.. What happens if diseases change abundance or remove these species from their habitats? WHAT HAPPENS? What COULD happen?

Image by Phil Williamson

Image by Daniel Johnson

The thing is, that BOTH of these species occupy important ecological positions. As mentioned earlier, Pisaster is a keystone species. The presence or absence of a keystone species in an ecosystem can dramatically change the interactions of that ecosystem.

For example, Ochre stars (Pisaster ochraceus) removed from the intertidal would likely result in a significant overgrowth of mussels and other invertebrates which ochre stars typically feed upon. Mussels might come to dominate an ecosystem and prevent other animals from inhabiting that area. There could be a cascade of other consequences of course...

What is perhaps most concerning is how MANY starfish species seem to be affected. Many of their ecological roles are poorly understood but are likely to be important. The effect on the ecosystem is likely to be significant.

Thanks to many discussions at Science Online Oceans this past weekend for discussions that inspired this post!

About Me

I pursue starfish related adventure around the world with a critical eye and an appreciation for weirdness.
Support has been courtesy of the National Science Foundation but the views and opinions presented herein are mine and do not reflect the opinions of them or any affiliated institutions.
Need to hire an invertebrate zoologist/marine biologist? Please contact me!